The beauty of science, as the article states, is that what we know can change on new data. Doesn't really matter which of these two models gains consensus. The model claiming 'weirdness that will go away', must put forth an extent for that weirdness. Once Voyager gets there, we will know if it is right or not.

Furthermore, it's so hard to tell if a single chord across a 3D volume is representative of anything anywhere else.

Even if Voyager comes back with measurements reinforcing the older model now that we know about the edge effects it'll be necessary to send more probes through other regions before we're comfortable we know what the nature of the boundary is everywhere.

If the particles are coming in perpendicular and then altering their velocity to run more or less parallel, eventually Voyager would have to get to a point where the particles are closer to perpendicular, right?

As I recall scientists have been arguing about whether Voyager has left the Solar System for the past twenty years. In 1993 I recall seeing a poll posted on a bulletin board in the U of C's department of Physics and Astronomy asking members of the faculty whether they thought Voyager 1 had crossed the heliopause yet. About half said yes, while the others guessed it would be anywhere from next month to next century before it happened. I still don't know which one of them was right.

The wonderful thing about where the Voyagers and Pioneers are going is that it really is where no one has gone before. We won't know for sure what is ahead of them until it is already behind them.

I think it is great that we launced Voyager back in the 1970's and it is still performing useful science. Smart phones have been out for less than ten years and I already have a draw full of them. I know it is not an apples to apples comparison, but it is clear that Viking is a monumental achievment.

Wasn't there another Voyager trailing this one? Will it be going out the same way? Will it be able to provide additional insight?

When you think about Voyager, it really is one of mankind's crowning achievements to date. Easily as much of an accomplishment as placing a man on the moon or the incredible life of rover's Spirit and Opportunity. Tell me again, why we're not building ships in a space shipyard near to the ISS for travel abroad? *boggles the mind*

RTGs (based on some quick research) are very power inefficient, compared to your average nuclear reactor. At best, an RTG manages about a 10% power conversion rate using whats called a thermocouple. 3-7 percent efficency is a more realistic average according to Wikipedia.

Basically, if you need to create a few hundred watts for a long time, and don't care a whole lot about emitted radiation as your radiation shielding degrades, RTGs are great.

If you want to provide a lot of power with nuclear -you need a reactor, where again they use the heat from fission to heat water, which then drives a steam turbine to create electricty. Which is far more power efficient.

RTGs (based on some quick research) are very power inefficient, compared to your average nuclear reactor. At best, an RTG manages about a 10% power conversion rate using whats called a thermocouple. 3-7 percent efficency is a more realistic average according to Wikipedia.

Basically, if you need to create a few hundred watts for a long time, and don't care a whole lot about emitted radiation as your radiation shielding degrades, RTGs are great.

If you want to provide a lot of power with nuclear -you need a reactor, where again they use the heat from fission to heat water, which then drives a steam turbine to create electricty. Which is far more power efficient.

On a specific power measure (power per mass) I bet the RTGs win once you factor in the weight of the reactor, turbines, etc. I honestly don't know which method extracts the most power per unit mass of fuel consumed.

RTGs (based on some quick research) are very power inefficient, compared to your average nuclear reactor. At best, an RTG manages about a 10% power conversion rate using whats called a thermocouple. 3-7 percent efficency is a more realistic average according to Wikipedia.

Basically, if you need to create a few hundred watts for a long time, and don't care a whole lot about emitted radiation as your radiation shielding degrades, RTGs are great.

If you want to provide a lot of power with nuclear -you need a reactor, where again they use the heat from fission to heat water, which then drives a steam turbine to create electricty. Which is far more power efficient.

On a specific power measure (power per mass) I bet the RTGs win once you factor in the weight of the reactor, turbines, etc.

Which is important if you're shooting something off the planet and want it to go anywhere. Every ounce counts when you're worried about delta V and getting around the solar system in a reasonable amount of time. Not so much if you want to do something back on the ground, or even in the atmosphere. The main benefit of RTGs, a very long lifetime without servicing, is pretty much a moot point when nuclear reactors are already so good that food and supplies becomes the limiting factor for things like subs and aircraft carriers.

It seems to me there may not be a single, clear line where the solar system ends and inter-stellar space begins. Perhaps it is more of band, like the beach. That is land, that is sea, but in the middle you have a shifting zone of waves and tides. It just seems like there are multiple criteria they are using to define the edge, and maybe they don't all line up.

There's no point in these "still not entirely sure if Voyager is outside the solar system yet" articles every couple of weeks... The debate will rage for months or years, and there's absolutely no urgency involved in the debate. Voyager 1 isn't dying any time soon, or anything like that. Neither are we waiting on it before we can do... SOMETHING. In a few years, Voyager 1 will be in interstellar space, and scientists will have tons of data to analyze on the edge of the solar system, and form new theories about what goes on there. In retrospect, we'll get it all figured out, and be able to name the exact date when Voyager crossed the threshold. In the mean time, just lay back and be happy that we're learning much from this process, and that there's still tons more for humanity to keep learning.

A thought just came to me... why the hell are we crashing Cassini into Saturn? Can't we find some way to sling that probe out as well? Get even more data about what exists out past the planets?

Likely there isn't enough fuel left to get enough delta V to reach escape velocity from Saturn.

The Voyagers were never in orbit around the gas giants. They came in fast, they left faster - and slowed them down in their orbits by the eensiest teensiest bit. Perhaps given several decades one could use Saturn's moons to gain enough delta V to start thinking about an escape trajectory - but likely not.

Okay, now time to build that ship to Proxima Centauri so we can go pick up the thing when it gets there.

None of the interstellar probes are aimed in the direction of Proxima Centauri, nor any other nearby solar systems. It'll be tens of thousands of years before they even distantly approach one, with no power, and still so distant that the "nearby" solar system would similarly just be a little blue dot.

It seems to me there may not be a single, clear line where the solar system ends and inter-stellar space begins. Perhaps it is more of band, like the beach. That is land, that is sea, but in the middle you have a shifting zone of waves and tides. It just seems like there are multiple criteria they are using to define the edge, and maybe they don't all line up.

Yes, there is a "band", it's called the heliosphere. And no, there's no room for dispute about where the "edge" is, any more than you'd argue about where one wave in a pond ends, and the other begins. The dispute is because the sensor readings just don't correlate with what astrophysicists expected to see, so maybe the theories are all wrong (and to what degree we don't know) or the location of the edge is wrong, we're just not there yet, and there's something weird going on in the heliosphere (before the edge) that we didn't anticipate.

So about Voyager's power system. Is there a reason we don't use RTG's more on earth? Their lifespan and apparent reliability is pretty fascinating.

1) You trade reliability for efficiency. RTGs use the Peltier/Seebeck effect to generate electricity, the reverse of a mini-fridge or 12V ice chest. For the benefit of reliability with no moving parts, obscene amounts of energy are wasted in this inefficient conversion method. NASA has been developing much more efficient but non-solid state SRGs to replace RTGs.

2) Plutonium-238 is very expensive, and currently scarce. Even in a much more efficient SRG, the cost of the Plutonium-238 to power a car would cost much more than a house. Here on this side of the asteroid belt (eg. here on Earth) PV Solar panels are much cheaper, lighter, more flexible, and offer more power.

3) Plutonium-238 and any other energetic alpha emitters are dangerous. Not like gamma-emitters used in nuclear reactors, where months of exposure will make you sterile, bald, and sick. More like a few inhaled particles will kill you in no time. Would you like a battery powered by anthrax?

When you think about Voyager, it really is one of mankind's crowning achievements to date. Easily as much of an accomplishment as placing a man on the moon or the incredible life of rover's Spirit and Opportunity. Tell me again, why we're not building ships in a space shipyard near to the ISS for travel abroad? *boggles the mind*

Because the ISS is in a completely wrong orbit for any kind of launching to… pretty much anywhere. The amount of time / material it takes to haul and assemble materials to the ISS, put it together, then navigate that vehicle into any kind of remotely usable spot for proper launching into proper orbit or a distant destination is far outweighed by just doing it properly on the ground.

With all the pop culture reference I thought I'd throw in this for completeness. From our friends at Futurama.[img]http://www.google.com/imgres?safe=off&hl=en&biw=1600&bih=775&tbm=isch&tbnid=vb5MRuc4GwQMxM:&imgrefurl=http://futurama.wikia.com/wiki/V-GINY&docid=5X8b0Jqwknr3ZM&imgurl=http://images3.wikia.nocookie.net/__cb20100625042617/en.futurama/images/8/8d/V-Giny.png&w=330&h=320&ei=MJ4OUsj1OcXRigLi9oC4AQ&zoom=1&ved=1t:3588,r:0,s:0,i:81&iact=rc&page=1&tbnh=174&tbnw=161&start=0&ndsp=24&tx=75&ty=94[img]sorry for the cumbersome link I have not figured out how to get the image imbedded in the post